Micro-fluidic devices are used to manipulate microscopic volumes of liquid inside micro-sized structures. Applications of such devices include precise liquid dispensing, drug delivery, point-of-care diagnostics, industrial and environmental monitoring and lab-on-a-chip devices. Lab-on-a-chip devices can provide advantages over conventional and non-micro-fluidic based techniques such as greater efficiency of chemical reagents, high speed analysis, high throughput, portability and low production costs per device. In many micro-fluidic applications such as liquid dispensing, point-of-care diagnostics or lab-on-a-chip, a role of the micro-fluidic pumps is to manipulate micro-volumes of liquids inside micro-channels.
Micro-fluidic pumps generally fall into two groups: mechanical pumps and non-mechanical pumps. Mechanical pumps use moving parts which exert pressure on a liquid to move a liquid from a supply source to a destination. Piezoelectric pumps, thermo-pneumatic pumps, and electro-osmotic pumps are included in this group. An electro-osmotic pump uses surface charges that spontaneously develop when a liquid contacts with a solid. When an electric field is applied, the space charges drag a body of the liquid in the direction of the electric field.
Another example of a non-mechanical pump is a pump exploiting thermal bubbles. By expanding and collapsing either a bubble with diffusers or bubbles in a coordinated way, a thermal bubble pump can transport liquid through a channel. Several types of thermal bubble pumps are known in the art.
Micro-fluidic bubble pumps are typically used to move micro quantities of fluid from a supply location to a destination so that a metered amount of liquid is delivered to the destination location. However, there is a need to deliver metered quantities of vaporized fluids from a supply location to a destination for various applications including vapor therapy, flavored e-cigarettes, chemical vapor reactions, and the like.
One problem with conventional bubble pumps is that the bubble pumps are limited by size and fluid flow constraints. Increasing the number of bubble pumps and the length of the bubble pumps increases the volume and pressure, respectively of liquid flowing out of the bubble pumps, and also increases the area required for dispensing liquids from the bubble pumps. For some applications, the size of the bubble pumps is critical. Accordingly, conventional bubble pumps may not be useful in a variety of applications that may require a small size with higher fluid pressures and/or increased fluid flow volumes.
In view of the foregoing, there is a need to provide a micro-fluidic vapor from a reduced size micro-fluidic ejection device. Accordingly, there is provided, in one embodiment, a micro-fluidic device. The device includes a semiconductor substrate attached to a fluid supply source. The substrate contains at least one vaporization heater, one or more bubble pumps for feeding fluid from the fluid supply source to the at least one vaporization heater, a fluid supply inlet from the fluid supply source in fluid flow communication with each of the one or more bubble pumps, and a vapor outlet in vapor flow communication with the at least one vaporization heater. The one or more bubble pumps each have a fluid flow path selected from a linear path, a spiral path, a circuitous path, and a combination thereof from the supply inlet to the at least one vaporization heater.
In another embodiment of the disclosure there is provided a method of vaporizing two or more fluids in micro-fluidic quantities. The method includes feeding two or more fluids to a micro-fluidic device that includes a semiconductor substrate attached to a fluid supply source. The substrate contains at least one vaporization heater, two or more bubble pumps for feeding fluid from the fluid supply source to the at least one vaporization heater, a fluid supply inlet from the fluid supply source in fluid flow communication with each of the two or more bubble pumps, and a vapor outlet in vapor flow communication with the at least one vaporization heater, wherein the two or more bubble pumps each have a fluid flow path selected from a linear path, a spiral path, a circuitous path, and a combination thereof from the supply inlet to the at least one vaporization heater. The two or more bubble pumps are energized to provide the two or more fluids to the at least one vaporization heater, the two or more fluids are vaporized with the at least one vaporization heater.
A further embodiment of the disclosure provides a method for reacting and vaporizing micro-fluidic quantities of two or more different fluids. The method includes providing a micro-fluidic device that contains a semiconductor substrate attached to two or more fluid supply sources. The substrate includes at least one vaporization heater, a bubble pump for feeding fluid from each of the two or more fluid supply sources to the at least one vaporization heater, a fluid supply inlet from each of the two or more fluid supply sources in fluid flow communication with each bubble pump, and a vapor outlet in vapor flow communication with the at least one vaporization heater, wherein each bubble pump has a fluid flow path selected from a linear path, a spiral path, a circuitous path, and a combination thereof from the supply inlet to the at least one vaporization heater. Each bubble pump is operated to provide the two or more different fluids to the at least one vaporization heater. The two or more fluids are reacted on the at least one vaporization heater to provide a reaction product, and the reaction product is vaporized with the at least one vaporization heater.
Accordingly, embodiments of the disclosure provide a compact micro-fluidic vaporizing device that may be used to mix and/or react and vaporize fluids for a variety of applications. The devices enable the pumping and vaporization of fluids at higher pressure than conventional devices and enable larger quantities of fluids to be vaporized without increasing the size of the device.